The present invention relates to controllers for irrigation sprinklers and, more particularly, to an improved automated irrigation system having localized moisture needs input to the control function comprising, a sprinkler head connected to a supply of water under pressure by a pipe having a valve therein; moisture sensing probe means placed in the soil adjacent the sprinkler head for developing an electrical signal representing the moisture content of the soil surrounding the probe means; and, irrigation bypass logic means disposed at the probe means and operably connected to the valve and the probe means for comparing the moisture content of the soil surrounding the probe means to pre-established limits and for preventing the valve from supplying water to the sprinkler head when there is sufficient moisture in the soil.
Irrigation sprinkler systems tend to undergo little improvement with time and that progress which is made is mostly an adapting of new materials to old processes. Thus, the design of sprinkler heads originally fabricated out of metals has been copied in plastics. Likewise, the control functions originally accomplished with clock motors, cams and switches has now been copied with electronics. The result, in most cases is a system which looks "state-of-the-art" to the consumer but which, in fact, falls far short of providing adequate control of the irrigation function for the areas being watered by the system. This is true for both the small home user and the large commercial users such as golf courses, and the like. A typical blatant and irritating indication of the failure of these supposedly state-of-the-art irrigation control systems is seeing the sprinklers in an area operating in the rain during a drought. Not only that, most individuals do not known how to water plants properly. They either water too much or not enough. They also water in a manner which does not promote adequate root growth. As a result, in any water deprivation situation, the plants quickly die. With the conventional irrigation control system, it is these very people who program the controller. Since they don't know how to water, they simply set up the controller to water in the same wrong manner and assume that now that their irrigations have been turned over to the automated device, they no longer have to worry. Of course, when the plants die, they blame the irrigation system.
The typical approach to irrigation as employed in most control systems is depicted in FIGS. 1-3. An input pipe 10 connected to a source of water under pressure is connected to a plurality of valves 12 (only one being shown for simplicity) at a main site such as a garage, clubhouse, building basement, or the like. A controller 14 is placed adjacent the valves 12 and operably connected thereto with wires 16. The controller 14 is connected to an appropriate source of power (not shown), which is the reason that the controller 14 and valves 12 are all placed close adjacent the main site. Since multiple conductor wire as typically employed for the wires 16 is costly and a bother to bury in trenches between the controller 14 and valves 12, they are usually located within feet of each other. Each valve 12 has a branch pipe 18 connected thereto which extends from the main site to a remote site where there are to be a plurality of sprinkler heads 20 attached to riser pipes 22 connected into the branch pipe 18. In a typical yard for a home, the branch pipes 18 only extend 50-100 feet typically. In a golf course, or the like, they can extend by orders of magnitude.
Again, it is also typical that the sprinkler system is installed with virtually no relationship to the type of plants that are to be irrigated thereby. Even in high priced landscaping undertakings like golf courses, hotel grounds, etc., the landscaping is done by one entity and the irrigation system is installed by another entity with only a rough layout map to work from. It is generally assumed by all concerned that if the area is covered by a grid of sprinkler heads 20, the state-of-the-art irrigation control system will have no problem in properly watering the area. Nothing could be further from the truth. Once the landscaping has been completed and the operation of the system has been turned over to others, the failure of the system does not become apparent immediately. Rather, there is a continuous and insidious replacement of plants which have died--because of everything but the irrigation system. In the rare case where the failures of the irrigation system are recognized, the cost and inconvenience of digging up the old system and reinstalling it are generally a deterrent to actually accomplishing a meaningful modification. The management of an operating golf course is not about to shut the place down and allow trenches to be cut through the fairways to relay irrigation pipe. Thus, sprinkler heads 20 may be replaced and "adjusted" to vary flow rates and the watering times for the controller 14 may be varied; but, the system will not be made to work properly. Various plants with differing watering requirements being watered from a common branch pipe 18 will have to suffer (and probably die). Either some will be over watered or some will be under watered.
There has been some recognition in the art that it is stupid to operate the sprinkler system when it is raining (or has rained recently). Most controllers 14 have a "rain switch" that can be placed in a "rain" position when the operator knows that rain will take care of the irrigation for a given period. The rain switch merely disconnects the connection to the wires 16. In other regards, the controller 14 continues to operate. If the operator forgets to set the switch, the irrigation system operates anyway (including during a downpour). If the operator forgets to return the switch to its operating position, nothing gets watered at a later date and dries up. For the homeowner, this means having to have a "controller sitter" for the irrigation system when on vacation. It also means trudging through the rain and wet grass to turn off a controller mounted on the outside of the house that is watering the lawn during the rain.
Some controllers 14 have a series connection (like the above-described rain switch) to which a "rain sensor" can be operably connected. The typical rain sensor is a pan with a float connected to a switch. When it rains, the pan fills with water. If there is sufficient water in the pan to cause the float to operate the switch, the irrigation system is disconnected from the valves 12. A more exotic variation of that prior art approach is depicted in FIG. 2. In this case, a moisture sensor probe 24 is inserted in the ground to test the moisture content thereof. For the reasons set for above relative to running wires between components, the probe 24 is placed close to the controller 14 or the valves 12, whichever is most convenient. This prior art approach presupposes that the moisture content of the soil where the probe 24 is located is a proper indication of the moisture content of the soil throughout the system. Except in rare instances, that is a brash assumption which can lead to improper watering and, once again, dead plants.
It should also be mentioned in passing that some commercial irrigation systems provide a tank 26 for containing liquid fertilizer. The tank 26 is connected to the branch pipes 18 (or the input pipe 10) by a connecting pipe 28. A manual or automated valve (not shown) can be opened to allow the fertilizer to be mixed with the irrigation water and thereby fertilize the plants. Such systems are quite common for systems used in the irrigation of crops and hydroponics. Simple versions of this approach are also available for the home waterer, and the like. The mixer/dispenser connects to a hose bib and the hose is connected to the mixer/dispenser. Fertilizer pellets (or liquid) is placed in the mixer/dispenser which causes the fertilizer to be mixed with the water coming out of the hose.
Wherefore, it is the object of the present invention to provide an irrigation system which accurately controls the irrigation of areas as a function of the moisture content of the soil of the area.
It is another object of the present invention to provide an irrigation system which can be employed to retrofit existing irrigation systems with a minimum of inconvenience.
It is still another object of the present invention to provide an irrigation system which can easily adapt to the special watering needs of different plants within a given area.
It is yet another object of the present invention to provide an automated irrigation control system which can be added to present manual systems with a minimum of modification and digging.
It is a further object of the present invention to provide an irrigation system which includes fertilizing capability which can easily adapt to the special needs of different plants within a given area.
Other objects and benefits of the present invention will become apparent from the description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.